In defining a pattern on a substrate, the shadow masking technique is well known. It allows efficient fabrication of patterns by replacing the conventional lithography cycle which includes deposition, photo and etch process steps by just one single process and machine. In common shadow masking techniques an emission source which may for example emit electromagnetic radiation, elementary particles or materials is directed to a substrate like for example a polished silicon slice. Between the emission source and the substrate there is provided a shadow mask with one or more apertures. The emission is directed through the aperture of the shadow mask and at the substrate, thereby producing changes on or in the substrate in a region of the substrate where the emission impinges. The shadow masking technique allows fabrication of complex patterns having a high density.
In U.S. Pat. No. 6,313,905 B1 there is disclosed an apparatus for defining a pattern on a substrate, said apparatus using the above-mentioned shadow masking technique. The known apparatus comprises an evaporation source and a material source, respectively. Said source emits an emission directed to a substrate holder on which the substrate is positioned. The apparatus further comprises a moving portion which consists of an elongated flexible member and a tip, said tip moving over the surface of the substrate during patterning. The flexible member has an aperture so that the emission from the emission source could pass the flexible member through said aperture and impinge on the substrate. By moving the movable portion above the substrate a variety of different patterns could be generated on or in the substrate. The tip of the flexible member proves advantageous because the tip is able to follow the surface of the substrate very closely when scanning the surface. The tip is primarily used as a distance-controlling means thus allowing one to position the flexible member which acts as a shadow mask in close and at a well defined distance to the surface of the substrate. However, the tip may further be used for pattern inspection, inspection of electrical properties, in-situ functional testing etc., i.e. the tip is further used for inspecting the properties of the pattern and the substrate, respectively. In a special embodiment of the known apparatus the Atomic Force Microscopy (AFM) principle is used for distance regulation and for identifying nano-scale features of the pattern, said moving portion consisting of a common cantilever with a tip, wherein the cantilever comprises the above-mentioned aperture.
The known apparatus proves itself, however, it has still some disadvantages which have not been overcome yet. First of all it should be mentioned that the known apparatus is not able to create patterns in a large area of the substrate in an appropriate time, i.e. in order to create a pattern in a large area the moving portion has to be moved over the whole area which leads to a loss of time so that an efficient and thus cheap prototyping of nano-structures is prevented even if larger flexible members are used. Above this, the known apparatus does not allow one to use a variety of different masks, instead it can only use the mask being defined by the flexible member with its apertures. Therefore, the flexibility of the known apparatus is limited. Further, the inspection of the properties of the generated pattern has to be performed immediately after the generation of a certain part of the pattern to be inspected, since after the generation of the whole pattern it will be difficult to retrieve that certain part of the pattern. In the latter case a difficult and time consuming search for that certain part of the pattern has to be carried out.